Clif and Crystal Williams of Willow Springs, along with her children, Cheyenne, 9; Sierra, 8; Savannah, 6; Patrick, 3; Jade, 2; and Sage, 3 weeks, enjoy using their rocket mass heater as an updated version of an earthen oven.

The Williams moved from Oklahoma to Willow Springs in 2005 to be closer to family.

“Since then, half of my family has also moved into the area to make one huge family,” said Crystal.

Building the rocket stove was Crystal’s idea and it became a family project.

“Our family had a great time building the stove, from start to finish. It can take a while, depending upon the design and final look that you want it to have,” said Crystal.

The materials needed to build the stove are not costly.

“To build our rocket mass heater, we used cob, which is a mixture of clay, sand and straw, and we built the internal chamber from fire brick,” said Crystal.

“We also used an old water heater and a 55-gallon drum,” added Crystal, who relied on descriptions in Ianto Evans’ book “Rocket Mass Heaters.” “The materials are really easy to locate and can be salvaged, so the cost is very minimal. Our stove cost right around $100 to build.”

For step by step instructions to build the heater, Crystal recommends visiting http://www.rocketstoves.com/ and purchasing Evans’ book.

“The most complicated part of building a rocket mass heater is the J chamber and its technology,” said Crystal. “Once you have that fitted and mortared in place, the rest is fairly easy.”

“Not that mixing cob is easy work because it isn’t,” Crystal noted. “However, it’s very rewarding to use the skills you learned as a child making mud pies, and turn it into something that can heat your home, as well as cook your meals and heat your water.”

Once the stove is built, it is fueled by wood.

“The stove works by using ‘squaw’ wood, which is really just slang for wood you can find laying around on the ground,” said Crystal.

The cob provides insulation.

“The cob is a perfect complement to the stove design because it acts as a heat battery to store heat. The rule of thumb is for every inch of cob you have in thickness, you will have one hour of latent heat stored after the fire burns out,” explained Crystal. “This is a super-efficient wood stove, because you aren’t losing heat directly out the chimney. You are storing it by running it through the cob before you get to the exit flue.”

The heater can be used for cooking anything you would cook on top of a modern stove.

“It is an added bonus that you can use normal pots and pans directly on top of the 55-gallon barrel and cook a meal just as you would on your kitchen stove,” said Crystal. “A Dutch oven placed up side down will also bake some very nice apple strudel.”

Crystal suggests starting out small and planning for the cobbing to take time.

“You can build this stove easily in a weekend, however, cobbing the bench will take much longer,” said Crystal. “Cobbing is addictive, so watch out for that. The best advice I can give is start small, so that you don’t get overwhelmed and work one section at a time.”

For additional information on rocket mass heater stoves, visit http://www.rocket stoves.com/